1. Field of the Invention
The present invention relates to communications systems and more particularly to a communication system capable of transmitting data messages and for receiving and storing data messages in a communication receiver.
2. Background Discussion
Communication systems in general and paging systems in particular using transmitted call signals have attained widespread use for calling selected receivers to transmit information from a base station transmitter to the receivers. Modern paging receivers have achieved multifunction capability through the use of microcomputers which allow the paging receiver to respond to information having various combinations of tone, tone and voice, or data messages. The information is transmitted using any number of paging coding schemes and message formats. The prior art paging receivers have also provided such features as storing the data messages in a memory of the paging receiver for allowing the user to recall the messages at a later time. Other features have been the ability of paging receivers to provide a visual indication to the user of the receipt of a message, the ability to store the messages to be read at a later time, and the number of messages which have been received.
A typical memory display pager stores a plurality of received messages in a memory of the paging receiver. In the operation of such paging receivers, important factors involved in their successful operation is the portability of the receiver, the limited energy available for storing the messages and for the receiver, the amount of memory available for the paging receiver's processing unit, the limited availability of the radio spectrum, the fast response time required in today's active society, and the number of paging receivers included in a paging system. In such paging receivers, in order that the drain on the battery may be minimized, the paging receiver is systematically turned off and on to maximize the length of time energy is available from the batteries. Limited energy in which the paging receiver must operate limits the memory and minimizes the electronic circuitry such as the memory in the paging receiver. In the case of sending data messages, the data messages are limited because of the limited amount of memory available for operation of the paging receiver. Within these constraints, a paging receiver must commercially operate.
A particular problem with the prior art paging receivers is
the situation in which the paging receiver's memory is full and a message received or previously stored is lost because of the lack of memory available to store the message. Therefore, it would be highly desirable to have a paging receiver which alerts the user of the impending destruction or loss of a data message.